The present invention relates to ultrasonic probes for transmitting and receiving an ultrasonic wave signal into and from an object such as a blood vessel having an extremely small diameter with the ultrasonic transmission direction being mechanically changed, and is applicable particularly, but not exclusively, to an ultrasonic diagnostic apparatus which is for obtaining an ultrasonic cross-sectional image of the object, and further relating to ultrasonic diagnostic apparatus equipped with an ultrasonic probe.
Recently, noted is an operation technique that a trouble such as a stricture and imperformation within a blood vessel is diagnosed and treated through a catheter such as disclosed in the document U.S. Pat. No. 5,000,185. However, since in conventional arrangements a guidewire is connected to a tip portion of the catheter, in the case of searching a narrow blood vessel, the entire catheter is required to operate within the blood vessel, and in addition, although the guidewire is required to move in accordance with the top of the catheter being moved toward a target portion within the blood vessel, difficulty is encountered to move the catheter when an extremely narrow blood vessel exists which does not allow the passage of the guidewire.
Moreover, for example, for inserting the catheter into a coronary artery of a heart, the outer diameter of the catheter is required to be reduced up to a predetermined value and hence the ultrasonic transducer is required to be extremely small and thin. However, the reduction of the thickness of the ultrasonic transducer tends to increase the oscillation frequency, thereby making it difficult to construct an ultrasonic probe which can transmit an ultrasonic wave having a desired frequency. According to the conventional ultrasonic probes, since there are a number of parts having complicated configurations, difficulty is encountered to reduce the dimension of the ultrasonic probe up to a desired degree. In addition, according to the conventional probes, the ultrasonic image (ultrasonic cross-sectional image) is limited to a two-dimensional ultrasonic image in the radial direction.